Study: Erosion Program Increases Bird Populations

WEST LAFAYETTE, Ind. -- A study of the federal Conservation
Reserve Program, an agricultural program aimed at reducing erosion,
finds that the program also provides suitable bird habitat for many
declining species of grassland birds.

"The Conservation Reserve Program has been critical to help stem
the decline in grassland bird populations in the north central region,"
says Harmon Weeks, professor of wildlife at Purdue University.

The Conservation Reserve Program, or CRP, was established by
Congress in the 1985 Food Security Act, commonly known as the '85
Farm Bill. It was designed to control soil erosion and to limit
agricultural production to provide price stability. Through the
program, farmers receive payments for setting aside tracts of land for
a mandatory 10-year period. So far 31 million acres have been taken
out of agricultural production, although the 1996 Farm Bill authorized
up to 36.4 million acres to be retired at any one time out of an eligible
240 million acres.

Researchers from six universities in the north central region of the
United States compared the CRP lands that had been set aside to land
that was being farmed over a five-year period to determine whether
the program was providing usable habitat and for which species.

"Just the presence of birds isn't enough. It's really only good habitat
if they are successfully breeding," Weeks says. "These small grassland
birds have a high annual turnover in their populations -- over 50
percent for many species. If you don't replace this turnover, you have
a real problem."

Mark Ryan, a wildlife biologist at the University of Missouri, says
the study found that CRP lands are beneficial. "The work clearly
demonstrates the enormous use of CRP land by birds for
reproduction," he says. "CRP is providing substantial breeding
habitat."

The study examined bird populations in both CRP land and in
nearby land being used to grow row crops such as corn and soybeans.
Only farmland that was being planted using no-till methods was
examined, however.

Census counts were conducted in winter as well as summer.
"Different birds use CRP lands in the winter, and they use the CRP
habitat for different things," Ryan explains. "Some birds use CRP
lands in the summer for their nests. In the winter, other birds use CRP
lands as habitat because they provide cover from the weather and from
predators."

The study found that the most common species wintering in CRP
lands were ring-necked pheasant, American tree sparrow, northern
bobwhite, dark-eyed junco and American goldfinch. The most
common species in farm fields included horned lark, American tree
sparrow, European starling, mourning dove, lapland longspur,
meadowlark and Canada goose. Not surprisingly, bird species that
typically frequent agricultural row-crop fields are experiencing long-
term population increases that mirror the increases in the number of
acres planted in these crops.

Although the study didn't do a long-term comparative analysis, the
researchers say that the program appears to be helping to stop the
decline in the populations of many bird species.

During the preceding two decades, bird populations had decreased
as much as 90 percent in some areas, wildlife scientists say.

"It was a staggering decline," Weeks says. "In Illinois, some species
saw a 90 percent decline over a couple of decades. It was almost
catastrophic for these species."

A variety of changes in American rural society over the past 50
years have brought about the rapid decline in bird populations:

-- Fewer family farms resulted in a less diversified landscape, which
reduced habitat.
-- Improved farm production methods left fewer rough or odd areas
of fields unplanted.
-- Industrialized livestock production reduced the need for farmers to
leave land in pasture.
-- Many farmers switched from growing small grain crops to
growing crops such as corn or soybeans.
-- Increasing suburbanization of many areas further fragmented and
isolated available habitat.

Although the Conservation Reserve Program seems to have
stemmed the decline in many species of grassland birds, the
researchers caution that bird populations are still at risk.

"These increases may be ephemeral" Weeks says. "If next year all
of these areas are planted in row crops, those birds are all dead. They
have to place else to go. They can't just crowd into some other,
smaller area. It simply doesn't work that way.

"If Congress hadn't kept the Conservation Reserve Program in the
'96 Farm Bill, it would have been devastating to the populations of
quail, pheasant and songbirds."

One success story of the CRP set-aside is in the numbers of
ringneck pheasant. Minnesota saw a threefold increase in pheasant
population from 1984 to 1991, and in Dixon County, Neb., the
pheasant population increased at least fivefold from 1985 to 1994. The
areas that had the most success with pheasant population were those
that had about 20 percent of the farmland in set-aside. The researchers
speculate that the dense cover of CRP lands sustains the populations
by providing thermal cover during harsh winter weather.

The story isn't so positive for another popular game bird, the
bobwhite. The study found no evidence of an increase in bobwhite
populations brought about by the CRP set-aside.

Although most farmers enjoy having gamebirds on their property,
some other species are not welcome.

"All farmers delight in having some wildlife on their farms if it
doesn't hurt crop production," Weeks says. "Unfortunately, some of
the species that have the highest populations, such as the red-winged
blackbird, are birds that are occasionally harmful to agriculture."

In the case of some of these birds, however, raw population
numbers might not be telling the entire story. According to Ryan,
follow-up research in Missouri has found that although the population
numbers for the blackbirds may be high, that doesn't mean that their
numbers are increasing. In fact, there is some evidence that CRP land
is causing a slight decrease in blackbird populations.

"This surprised the heck out of us," Ryan says. "Everybody just
assumed that because of CRP habitat, the number of blackbirds was
increasing.

Ryan says there may be a simple explanation. "Blackbirds nest
either in wetlands or in grasslands. In the CRP lands (grasslands) the
nests are an easy victim to predators. In the grasslands, the blackbirds
also have their nests taken over by parasitic brown-headed cowbirds,"
he says.

"In essence, CRP lands aren't good habitat for red-winged
blackbirds, even though you find a lot of them in the set-aside land."

NOTE TO JOURNALISTS: The researchers involved in the study
mentioned in this news release were Louis B. Best, Department of
Animal Ecology, Iowa State University; Henry Campa III and Scott
R. Winterstein, Department Fisheries and Wildlife, Michigan State
University; Kenneth E. Kemp and Robert J. Robel, Division of
Biology, Kansas State University; Mark R. Ryan, The School of
Natural Resources, University of Missouri; Julie A. Savidge,
Department of Forestry, Fisheries and Wildlife, University of
Nebraska; and, Harmon P. Weeks Jr., Department of Forestry and
Natural Resources, Purdue University.

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